"We are ready for talks, and negotiations have never been interrupted by us," the official Irna news agency reported him as saying.

The newly installed president said he would put forward new proposals for negotiation after forming a cabinet.

An Iranian official involved in the negotiations, Sirus Naseri, told the Reuters news agency that an Iranian proposal to settle the standoff was "still on the table".

Iranian Defence Minister Ali Shamkhani said that Tehran would "resist" mounting international pressure and was unworried about threats of UN Security Council intervention.

The Isfahan plant is Iran's main uranium conversion facility. Conversion is an early stage in the nuclear fuel cycle, turning raw uranium - known as yellowcake - into the feedstock for enriched uranium.

Uranium enriched to a low level is used to produce nuclear fuel, while further enrichment makes it suitable for use in atomic weapons.

Mohammad Saeedi, deputy head of Iran's Atomic Energy Organisation, said on Monday that work at Isfahan had resumed under the supervision of the IAEA.

He later said that work would begin on Wednesday in previously sealed-off areas of the plant, taking the conversion process further.